start second exercise

Lösungen_N/nnwplot.py

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+# based on: https://github.com/eakbas/tf-svm/blob/master/plot_boundary_on_data.py
+import numpy as np
+from matplotlib import pyplot as plt
+from matplotlib import colors
+
+
+def plotTwoFeatures(X,T,pred_func):
+    if X.ndim!=2:
+        raise ValueError('X be a matrix (2 dimensional array).')
+    tp=False
+    if X.shape[0]!=2 and X.shape[1]==2: 
+        X=X.T
+        tp=True
+    if X.shape[0]!=2:
+        raise ValueError('X must contain exactly 2 features.')
+        
+    # determine canvas borders
+    mins = np.amin(X,1); 
+    mins = mins - 0.1*np.abs(mins);
+    maxs = np.amax(X,1); 
+    maxs = maxs + 0.1*maxs;
+
+    ## generate dense grid
+    xs,ys = np.meshgrid(np.linspace(mins[0],maxs[0],300), 
+            np.linspace(mins[1], maxs[1], 300));
+
+
+    # evaluate model on the dense grid
+    try:
+        Z = pred_func(np.c_[xs.flatten(), ys.flatten()].T);
+    except:
+        Z = pred_func(np.c_[xs.flatten(), ys.flatten()]);
+
+    if tp:
+        Z=Z.T
+        T=T.T
+    
+    if Z.ndim>1 and Z.shape[0]>1: # onehot? -> convert
+        Z=Z.argmax(0)
+    Z = Z.reshape(xs.shape)
+    
+    if T.ndim>1 and T.shape[0]>1: # onehot? -> convert
+        T=T.argmax(0)
+        
+    # Plot the contour and training examples
+    plt.contourf(xs, ys, Z, cmap=plt.cm.Spectral)
+    plt.scatter(X[0,:], X[1,:], c=T, s=50,
+            cmap=colors.ListedColormap(['orange', 'blue', 'green']))
+    plt.show()